This invention aims to improve the structure of a PTC heater in such a way that the thermal energy given out of every PTC thermistor element can be utilized as efficiently as possible.
The better the heat dissipating coefficient of a PTC heater is, the higher its effectiveness is. One method of increasing the heat dissipating coefficient is to provide a PTC heater having a large area to conduct the heat produced by the PTC thermistor elements and to radiate it away from the PTC thermistor as much as possible.